Systematic review of the literature on comparative effectiveness of antiviral treatments for chronic hepatitis B infection

Exploring evidence-based innovative therapy for the treatment of chronic HBV infection: experimental and clinical

With the advent of various vaccines and antimicrobial agents during the 20th century, the control and containment of infectious diseases appeared to be a matter of time. However, studies unveiled the diverse natures of microbes, their lifestyle, and pathogenetic potentials. Since the ground-breaking discovery of the hepatitis B virus (HBV) by Baruch Blumberg and the subsequent development of a vaccine in the early 1980s, the main task of the scientific community has been to develop a proper management strategy for HBV-induced chronic liver diseases. In the early 1980’s, standard interferon (IFN) induced a reduction of HBV DNA levels, followed by the normalization of serum transaminases (alanine aminotransferase, ALT), in some chronic hepatitis B (CHB) patients. However, in the course of time, the limitations of standard IFN became evident, and the search for an alternative began. In the late 1980’s, nucleoside analogs entered the arena of CHB treatment as oral drugs with potent antiviral capacities. At the beginning of the 21st century, insights were developed into the scope and limitations of standard IFN, pegylated-IFN as well as nucleoside analogs for treating CHB. Considering the non-cytopathic nature of the HBV, the presence of covalently closed circular DNA (cccDNA) in the nucleus of the infected hepatocytes and HBV-induced immune-mediated liver damages, a new field of CHB management was initiated by modulating the hosts’ immune system through immune therapy. This review will discuss the nature and design of innovative immune therapy for CHB.

Global burden of HIV, viral hepatitis, and tuberculosis in prisoners and detainees

The prison setting presents not only challenges, but also opportunities, for the prevention and treatment of HIV, viral hepatitis, and tuberculosis. We did a comprehensive literature search of data published between 2005 and 2015 to understand the global epidemiology of HIV, hepatitis C virus (HCV), hepatitis B virus (HBV), and tuberculosis in prisoners. We further modelled the contribution of imprisonment and the potential impact of prevention interventions on HIV transmission in this population. Of the estimated 10·2 million people incarcerated worldwide on any given day in 2014, we estimated that 3·8% have HIV (389 000 living with HIV), 15·1% have HCV (1 546 500), 4·8% have chronic HBV (491 500), and 2·8% have active tuberculosis (286 000). The few studies on incidence suggest that intraprison transmission is generally low, except for large-scale outbreaks. Our model indicates that decreasing the incarceration rate in people who inject drugs and providing opioid agonist therapy could reduce the burden of HIV in this population. The prevalence of HIV, HCV, HBV, and tuberculosis is higher in prison populations than in the general population, mainly because of the criminalisation of drug use and the detention of people who use drugs. The most effective way of controlling these infections in prisoners and the broader community is to reduce the incarceration of people who inject drugs.

Management of chronic hepatitis B in children: an unresolved issue

Although a rather benign course of chronic hepatitis B virus (HBV) infection during childhood has been described, 3-5% and 0.01-0.03% of chronic carriers develop cirrhosis or hepatocellular carcinoma before adulthood. Considering the whole lifetime, the risk of hepatocellular carcinoma rises to 9-24% and the incidence of cirrhosis to 2-3% per year. The aim of this article is to review the current knowledge regarding the natural history and treatment of chronic hepatitis B in children and to focus on critical aspects and unresolved questions in the management of childhood HBV infection. A literature search was carried out on MEDLINE, EMBASE, and Web of Science for articles published in English in peer-reviewed journals from January 1980 to February 2013. The search terms used included "Hepatitis B virus infection," "children," "HBV," "interferon," "lamivudine," "adefovir," "entecavir," and "tenofovir." Articles resulting from these searches and relevant references cited in the articles retrieved were reviewed. The current goals of therapy are to suppress viral replication, reduce liver inflammation, and reverse liver fibrosis. Therapeutic options for children are currently limited, and the risk for viral resistance to current and future therapies is a particular concern. Based on the data available at this time, it is the consensus of the panel that it is not appropriate to treat children in the immune-tolerant phase or in the inactive carrier state. For children in the immune-active or reactivation phases, liver histology can help guide treatment decisions. Outside of clinical trials, interferon is the agent of choice in most cases; currently, available nucleoside analogs are secondary therapies.

What evidence exists to support antiviral treatment in children with chronic hepatitis B?

Many questions are unanswered on the optimal management of chronically HBV-infected children. Chronic hepatitis B is generally a mild disease in children; however, response to therapy is partial and limited to specific subgroups, and available drugs have no proven advantage on long-term course of disease versus no treatment, and are hampered by numerous limitations. Studies on the natural history of chronic hepatitis B and the long-term results of the therapeutic schedules adopted so far should be critically appraised. A balance between the potential benefits of the treatment and its side effects, and the spontaneous course of the disease left untreated should be made.

Low hepatitis B envelope antigen seroconversion rate in chronic hepatitis B patients on long-term entecavir 0.5 mg daily in routine clinical practice

AIM

Data from registration trials with highly selective patients have shown that hepatitis B envelope antigen (HBeAg)-positive patients with chronic hepatitis B respond well to entecavir (ETV) 0.5 mg daily, with an HBeAg seroconversion rate of 21% at 12 months. However, there are varying data on the treatment outcomes of ETV 0.5 mg daily in routine clinical settings, with seroconversion rates at 12 months ranging from 8 to 48% in studies limited to 44-90 patients from centers in Asia, Europe, and South America.

MATERIALS AND METHODS

In the present study, we examined long-term treatment efficacy and tolerability in 136 consecutive treatment-naive HBeAg-positive chronic hepatitis B patients treated between January 2005 and January 2011 with ETV 0.5 mg daily at community clinics and tertiary centers in the USA. The primary study end point was HBeAg seroconversion.

RESULTS

Sixty-one percent of HBeAg-positive patients were men, mean age 39 ± 12 years, median hepatitis B virus DNA 7.48 (3.7-9.8) log10 IU/ml, median alanine aminotransferase 67 (14-1077) U/l, and median treatment duration 18 (6-60) months. At months 12, 24, and 36, complete viral suppression rates were 41, 66, and 85% and HBeAg seroconversion rates were 4.8, 20, and 30%, respectively. No patients experienced adverse events or developed genotypic resistance to ETV.

CONCLUSION

In clinical settings, ETV is highly tolerable and potent at suppressing hepatitis B viremia; however, the rates of HBeAg seroconversion appear to be much lower than those reported, highlighting the importance of appropriate counseling and planning for long-term therapy.

Hepatitis B virus management to prevent reactivation after chemotherapy: a review

PURPOSE

Reactivation of hepatitis B virus (HBV) infection after chemotherapy can lead to liver failure and death. Conflicting recommendations regarding HBV screening in cancer patients awaiting chemotherapy mean that some patients at risk for HBV reactivation are not being identified and treated with prophylactic antiviral therapy.

METHODS

We performed a narrative review of the existing evidence regarding screening for and management of HBV infection among patients with cancer using Ovid Medline, PubMed, and the Cochrane Library.

RESULTS

Our review showed inconsistencies in the definition and management strategies for HBV reactivation. The timeframe of reactivation is variable, and its molecular mechanisms are not clear. There are five effective antiviral agents that can be used as prophylaxis to prevent reactivation of HBV infection in cancer patients; however, the optimal drug and duration of therapy are unknown. Reactivation is more commonly reported in patients with hematologic malignancies receiving rituximab treatment, but reactivation can occur after other chemotherapies and in patients with solid tumors. Screening with all three screening tests-HBsAg, anti-HBc, and anti-HBs-allows the most thorough interpretation of a patient's serologic profile and assessment of reactivation risk; however, decision-making and cost-effectiveness studies are needed to determine optimal screening strategies.

CONCLUSIONS

Prevention of reactivation of HBV infection depends on identification of patients at risk and initiation of antiviral prophylaxis, but data to guide screening and treatment strategies are lacking. Additional research is necessary to accurately define and predict reactivation, identify best antiviral treatment strategies, and identify cost-effective HBV screening strategies.

Detection of mixed populations of wild-type and YMDD hepatitis B variants by pyrosequencing in acutely and chronically infected patients

BACKGROUND

Lamivudine (LAM) is associated with the highest known rate of resistance mutations among nucleotide analogs used to treat chronic hepatitis B virus (HBV) infection. Despite this, LAM continues in widespread use, especially in combination therapies. The primary LAM resistance mutation (rtM204V/I) occurs in the YMDD motif of HBV polymerase. The aim of this study was to characterize Brazilian HBV isolates from acute and chronic cases by direct sequencing, and to identify HBV quasispecies in the YMDD motif using a pyrosequencing method capable of detecting single-nucleotide polymorphisms. HBV DNA from serum samples of 20 individuals with acute HBV infection and 44 with chronic infection undergoing antiviral therapies containing LAM were analyzed by direct sequencing and pyrosequencing methods.

RESULTS

Phylogenic analyses of direct-sequenced isolates showed the expected genotypes (A, D and F) for the Brazilian population in both acute and chronic infections. However, within genotype A isolates, subgenotype A2 was more frequently detected in acute cases than in chronic cases (P = 0.012). As expected, none of the individuals with acute hepatitis B had LAM-resistant isolates as a dominant virus population, whether detected by direct sequencing or pyrosequencing. However, pyrosequencing analyses showed that 45% of isolates (9/20) had minor subpopulations (4-17%) of LAM-resistant isolates. Among chronic patients undergoing LAM treatment, YMDD mutants were frequently found as a dominant virus population. In cases where wild-type virus was the dominant population, subpopulations of YMDD variants were usually found, demonstrating the complexity of HBV quasispecies.

CONCLUSIONS

YMDD variants were frequently detected as a minor population in acute HBV infection. The occurrence of pre-existing variants may lead to a high frequency of resistant mutants during antiviral therapy in the chronic phase. In chronic infection, detection of YMDD variants before virological or biochemical breakthrough might contribute to making better therapy choices and thus improving treatment outcome.

Clinical evidence for the regression of liver fibrosis

Fibrosis is a common pathological process for the majority of liver diseases which in a significant minority of patients leads to end-stage cirrhosis and/or hepatocellular carcinoma. Data emerging from small rodent models of chronic liver disease have demonstrated that fibrotic extracellular matrix can be remodelled and near-normal hepatic architecture regenerated upon cessation of injury. Moreover, regression of liver fibrosis in these model systems can be stimulated with drugs that target the activities of fibrogenic hepatic stellate cells. These findings are exciting as they suggest that established fibrosis is susceptible to regression and possibly even reversion. Alongside these experimental studies is a growing body of clinical data that suggest regression of fibrosis may also occur in liver disease patients for whom an effective treatment is available for their underlying liver injury. This paper provides an up-to-date review of the currently available clinical data and also considers technical caveats that highlight the need for caution in establishing a new dogma that human liver fibrosis is reversible.

Adherence, persistence, healthcare utilization, and cost benefits of guideline-recommended hepatitis B pharmacotherapy

OBJECTIVE

To compare pharmacotherapy adherence, persistence, and healthcare utilization/costs among US patients with chronic hepatitis B (CHB) initiated on an oral antiviral monotherapy recommended as first-line treatment by current national (US) guidelines vs an oral antiviral not recommended as first-line monotherapy.

RESEARCH DESIGN AND METHODS

In this retrospective cohort study, patients aged 18-64 with medical claims for CHB who initiated an oral antiviral monotherapy for CHB between 07/01/05 and 01/31/10 were identified from a large US commercial health insurance claims database. Patients were continuously enrolled for a 6-month baseline period and ≥90 days follow-up. They were assigned to 'currently recommended first-line therapy' (RT: entecavir or tenofovir) or 'not currently recommended first-line therapy' (NRT: lamivudine, telbivudine, or adefovir) cohorts.

MAIN OUTCOME MEASURES

Multivariate analyses were conducted to compare treatment adherence, persistence, healthcare utilization, and costs for RT vs NRT cohorts.

RESULTS

Baseline characteristics were similar between RT (n=825) and NRT (n=916) cohorts. In multivariate analyses, RT patients were twice as likely as NRT patients to be adherent (OR=2.09; p<0.01) and persistent (mean: RT=361 days, NRT=298 days; p<0.01) and half as likely to have an inpatient stay (OR=0.527; p<0.01). Between the two oral antivirals recommended as first-line treatment, even though pharmacy cost was higher for entecavir, mean total healthcare costs for entecavir and tenofovir were similar ($1214 and $1332 per patient per month, respectively). Similar results were also observed with regard to adherence, persistence, and healthcare use for entecavir and tenofovir.

CONCLUSIONS

A limitation associated with analysis of administrative claims data is that coding errors can be mitigated but are typically not fully eradicated by careful study design. Nevertheless, the current findings clearly indicate the benefits of initiating CHB treatment with an oral antiviral monotherapy recommended as first-line treatment by current guidelines.

Recent advances in the treatment of chronic hepatitis B

INTRODUCTION

At present, two strategies exist for the treatment of chronic hepatitis B (CHB): i) standard or pegylated interferon alpha (IFN) with mainly immune modulatory effects; and ii) nucleos(t)ide analogues (NA) with direct antiviral effects. The optimal treatment for an individual patient remains controversial.

AREAS COVERED

The treatment efficacy and prediction of response to antiviral agents for chronic hepatitis B are reviewed and discussed.

EXPERT OPINION

The rates of hepatitis B e antigen (HBeAg) and hepatitis B surface antigen (HBsAg) loss or seroconversion are continuously increasing in CHB patients after stopping a finite course of IFN, whereas long-term NA therapy is usually required to improve the adverse outcomes of CHB. Lower baseline HBV DNA level is a strong predictor for both sustained viral suppression and HBeAg seroconversion in patients receiving IFN-based as well as NAs therapy. In addition, HBeAg-positive patients with genotype A or B infection have better responses to IFN-based therapy than those with genotypes C or D infection. Furthermore, on-treatment predictors such as declines of serum HBV DNA, HBsAg and HBeAg levels may be helpful in making decisions of subsequent therapy. Regarding the association of host genetic factors with responses to antiviral therapy, current evidence is limited.